Mercury switch



March 19, 1940. K. WEMAN 2,194,239

MERCURY SWITCH Filed Jan. 17, 1939 Patented Mar. 19, 1940 UNITED STATES MERCURY SWITCH Klas Weman,

Djursholm, Sweden, assignor to A. B. Hg. Relay Patent, Stockholm, Sweden, a

company of Sweden Application January 17, 1939, Serial No. 251,414 In Sweden March 22, 1938 Is Claims, (Cl. zoo-152) My present invention relates to electric switches and it relates more particularly to such electric switches which consist of a closed vessel containing a body of mercury or some other conducting liquid which is connected to an outer electrode and also containing a switching member pivotally mounted in the vessel and consisting of a cup-shaped vessel of electric insulating material, said cup-shaped vessel being partly submerged in the conducting liquid and being adapted to receive a portion thereof.

It is a primary object of my invention to provide a multi-pole switch which is so devised as to be capable of interrupting and closing, alternatively or in sequence, two or more circuits which are controlled by the switch. With this and other objects in view, I have devised an electric switch in which the switching member is provided with one or more liquid spaces or cells 20 which are separated from each other and are provided with separate outer electrodes, said liquid spaces or cells being adapted, through a shifting of the switching member, to communicate with the liquid space of the outer vessel and/or 5 each other respectively over overflow edges, thresholds or the like provided in the walls of the liquid cells.

The invention will now be more fully described having reference to the drawing attached to this specification and forming part thereof. In the drawing,

Figure l is a vertical sectional view of a thermostatic switch according to a first embodiment of this invention.

Figure 2 shows said switch as viewed from one side in Figure 1.

Figure 3 is a horizontal section through the lower portion of the apparatus which contains 0 the switching member.

Figure 3a is an end view of the cup-shaped body shown in Figures 1 and 3.

Figures 4 and 5 are vertical sectional views of an electromagnetic switch according to a second 4 embodiment of the invention.

Figure 6 is a horizontal section through the lower portion of the apparatus according to Figure 5, showing the switching member as viewed from above.

0 Figure 7 is a vertical section on the line I-I in Figure 6.

Figure 8 is a vertical section of an electro-magnetic switch according to a third embodiment, showing the switching member in section, and

55 Figure 9 is a horizontal section through the lower portion of the apparatus, showing the switching member as viewed from above.

In all the embodiments illustrated, the switching member is disposed within an air-tightly closed vessel I, preferably consisting of glass. 5 The switching member consists of a cup-shaped body 2 which is partly submerged in a conducting liquid 3 contained in the vessel .I, said conducting liquid preferably consisting of mercury. The said cup-shaped body is mounted for swinging or rocking movement about a horizontal axis, either on a yoke 4 secured in the bottom of the vessel I so as to pass through the walls of the vessel, or on two pivots sealed in the walls. The yoke 4, which consists of metal, may also serve as an electrode for conducting the current to the liquid in the vessel I. The cup 2 is made of electric insulating material and is adapted to receive part of the liquid contained in the vessel I.

In the embodiment shown in Figures 1 to 3, the cup-shaped body 2 consists of a substantially spherical portion which is disposed centrally in the vessel I, said spherical portion being swingably mounted on the yoke 4 so that the swinging 26 axis of the cup will pass approximately through the centre of the sphere. By means of a dividing wall 5 passing through the centre, the cup 2 is divided into two liquid spaces or cells 6 and I each provided with a channel-shaped or spout- 30 shaped extension 8 or 9 respectively, said spoutshaped extensions extending in opposite directions from the spherical portion and at right angles to the swinging axis. The spouts 8 and 9 form such an angle with each other that when one spout, for example the spout 8, is submerged in the liquid along its entire length, as shown in Figure 1, the other spout 9 will be raised above the free level of liquid. In said position the liquid space 6 will be filled with liquid to the same level as in the outer vessel, the liquid contents in the cell 6 being then in electrically conducting relation to the liquid contents in the outer vessel. The apparatus illustrated is intended to be used in the first instance as a twopole reversing switch, and for said purpose it is provided with three electrodes which pass through the wall of the vessel I, the above mentioned yoke 4 constituting the electrode which is common to the two circuits. The two other electrodes I0 and II are so arranged as to reach down with their ends into the liquid cells 6 and 1 respectively. By rocking the cup 2 about its axis in the one or the other direction the common electrode 4 will be brought into conducting connection alternatively with the one or the other of the two electrodes ID or ll. Thus, in the position of the cup 2 shown in Figure 1 the electrode 4 will be in connection with the electrode l through the liquid contents in the cell 6. On rocking the cup 2 to its opposite end position, which is shown in dotted lines in Figure 1, the first mentioned connection will first be interrupted at the outer end of the spout 8, whereafter a conducting connection is established with the electrode H through the liquid in the cell 1. By arranging the swinging axis on a level with the centre of the cup. as shown in Figure 1, the advantage is gained that the shifting of the switching member can be eifected without considerable change of position of the greater part of the amount of liquid contained in the cup. In order to obtain a. rapid interruption of a circuit with a minimum of arcing it has been found to be suitable to provide, at the ends of the spouts 8 and 9, an upstanding edge or threshold as indicated at l and with the edge or threshold higher at the middle as shown in Fig. 3a so that prior to interruption the liquid will be divided into two thinner strings and as a consequence will be rapidly severed. In the shown embodiment the shifting of the vessel 2 is effected by means of a heat sensitive member consisting of a bimetallic strip l2 disposed in a tubular extension l3 of the vessel l and secured in the wall of the vessel at the upper end of said extension. The bimetallic strip 12 engages with the upper end of a pin 14 which is secured in the intermediate wall 5.

For practical reasons the angle through which the cup can be turned between its two outer positions must be comparatively small. Therefore, it may be necessary in practice to make special provisions to retard the closing of the circuits upon the shifting of the cup, or to accelerate the interruption of the current respectively, so that time will be provided for one circuit to become completely interrupted before the other circuit is closed. Such provisions are of less importance in a thermostatic switch, in which the shifting of the cup member takes place comparatively slowly. In electro-magnetic switches and particular- 1y when strong currents are to be interrupted, it is of great importance to secure successive interrupting and closing of the two circuits. In Figures 4 to 7 is shown an electro-magnetic switch constructed with such requirements in view. The cup 2a is here provided with three liquid cells I1, I 8, I 9 arranged sideby side along the swinging axis. For maintaining a definite level of liquid in all the liquid cells the intermediate cell I8 is always in open connection with the liquid 3 in the outer vessel through an aperture provided in the bottom of the cell. By shifting the cup 2d to two end positions the intermediate. liquid cell l8.can be brought to communicate alternately with two'other liquid cells I! or l9. For said purprme the cells I! and [9 are provided with spout-shaped extensions 2| and 22 similar to those shown in Figures 1 to 3, said spout-shaped extensions extending in opposite directions from a deeper centrally positioned substantially cylindrical portion, the points of interruption being arranged in the intermediate walls 23 and 24 at the end of the spouts 2| and 22. At said points the intermediate walls 23 and 24 form thresholds 25 and 26 having substantially the same shape as the thresholds l5 and I6 shown in Figures 1 to 3. To facilitate a rapid circuit interruption the spouts 2| and 22 as well as the corresponding end portions of the liquid cell l8 are comparatively shallow, the bottoms of said spouts and of the corresponding portions of the liquid cell l8 being furthermore so arranged that they will be raised above the liquid level in the respective liquid cells when the switching member occupies its intermediate position as shown in- Figures 4 and 7. The central cylindrical portions of the liquid cells have a considerably greater depth thereby having so large a volume as to be able to hold the greater portion of the liquid contents in the respective liquid cells when the switching member takes up any one of its end positions. In the end positions of the switching member the respective spout will thus contain only so much liquid as is required to form a liquid string which extends over the threshold 25 or 25 respectively.

In the shown example the cup 2a is arranged to be actuated by means of two electro-magnets 21 and 28 arranged externally of the vessel la at opposite sides of an armature 29 which is connected with the cup and which extends with its upper end into a tubular extension 30 of the vessel la. The cup is normally held in an intermediate position by means of a blade spring 3| secured at the end of the extension 30, said blade spring embracing the armature 29 with its lower end. When the electromagnet 28 is energized the cup is shifted to its right hand end position against the action of the spring 3!, an electric connection being then established between the electrode 4 and the electrode ll over the threshold 26. When the magnet 28 is deenergized, the cup will return to its intermediate position, the connection between 4 and H is then interrupted at the threshold 26. The interruption of the circuit is eifected rather rapidly, because the amount of liquid held in the spout 22 and in the corresponding part of the cell I8 is comparatively small and will readily run ofi to the central part of the respective liquid cell. By energizing the electromagnet 2! connection can be established in similar manner between the electrodes 4 and Ill over the threshold 25. In case the energization of the magnet 21 is effected simultaneously with the deenergization of the magnet 28 the arrangement must be such that the connection between 4 and It] cannot be closed until the connection between 4 and H has become completely interrupted. For said purpose the liquid cell I8 is provided with a centrally positioned contraction formed by portions 32 and 33 which project from the walls 23 and 24, said contraction serving to retard the flow of liquid from one end of the cell Hi to the other. A retardation is also effected by ridges 34 and 35 formed on the bottoms of the spoutshaped side portions of the liquid cells between said portions and the deeper central portion which exerts a certain resistance to the flow of the liquid. Said arrangements also prevent splashing of the liquid upon the shifting of the cup to an end position and upon its restoration to the intermediate position respectively. The tendency of the cup to swing about its intermediate position will then be damped by the upward pressure exerted by the liquid 3 in the vessel la on the spout-shaped side portions. A further damping effect can be obtained by arranging the swinging axis of the cup eccentrically above and in parallel with the geometric axis of the cup, causing the cup to move in the manner of a pendulum. The aperture 20 in the bottom of the liquid cell I8 should then, of course,

C be so dimensioned that the flow of liquid from the outer vessel will take place relatively slowly.

In the embodiment shown in Figures 8 and 9 the cup is provided with two liquid cells or spaces 36 and 31, the cell 36 only being adapted to communicate with the liquid space in the outer vessel, while the other cell 31 can communicate .the point of interruption with a spout-shaped extension 42 and with an upstanding edge or threshold 43 arranged in a manner similar to the threshold IS in Figures 1 to.3. The cup substantially has the shape of a semi-sphere or ellipsoid with respect to which the swinging axis is centrally arranged. In the shown example the cup is adapted to be shifted with the aid of a solenoid 44 and an armature 46 arranged and guided in a tubular extension 45 of the vessel lb, said armature 46 resting in its free condition with its lower end on a bridge 41 provided across the spout 42. In the position of the cup shown in Figure 8 the solenoid 44 may be assumed to be energized, the armature 46 being then held in a raised position so that under the action of the upward pressure exerted by the liquid in the vessel lb on the spout/42 the cup can take up the position in which the liquid cells 36 and 31 communicate with each other over the threshold 39. When the solenoid is deenergized the cup will be shifted under the action of the weight of the armature 46 to its other end position. The connection between the electrodes 40 and 4|- will then be first interrupted, whereaiter the electrode 40, which is the common electrode, will be brought into conducting connection with the electrode 4 through the liquid flowing over the threshold 43. On account of the curved shape of the liquid cell 36 the flowing out of the liquid through the spout 42 will be retarded so that the connection over the threshold 39 will be positively interrupted before any connection is established with the liquid, in the outer vessel.

I claim:

1. An arrangement in electric switches of the kind which consist of a closed vessel containing a conducting liquid. connected to an outer electrode and a switching member pivotally mounted in the vessel, said switching member consisting of a cup-shaped vessel of electric insulating material partly submerged in the conducting liquid and intended to receive a portion of the conducting liquid, said switching member being provided with liquid cells which are separated from each other and are provided with individual outer electrodes, said liquid cells being adapted on the shifting of the switching member to be brought into communication with the liquid space of the outer vessel and with each other respectively over overflow edges provided in the walls of the liquid cells. 7

2. An arrangement according to claim 1, characterized in that the liquid cells are arranged substantially centrally about the swinging axis of the switching member and the overflow edges are arranged peripherally in such a manner as to become operative in diflerent angular positions of the switching member.

,3. In an electric switch, a closed vessel containing a conducting liquid connected to an electrode, a switching member pivotally mounted in the vessel and consisting of a cup-shaped vessel oi. electric insulating material partly submerged in the conducting liquid and adapted to receive a portion of the conducting liquid, said switching member having a plurality of liquid cells separated from each other, an individual outer electrode associated with each cell, said cells being adapted on shifting of the switching member to communicate the cells with the vessel over end edges of the cells.

4. An arrangement according to claim 3 in which the liquid cells are arranged adjacent the swinging axis of the switching member, and the overflow edges are spaced therefrom in such a manner as to become operative in different. angular positions of the switching member.

5. In an electric switch, a closed vessel containing a conducting liquidconnected to an outer electrode, a switching member pivotally mounted in the vessel consisting of a cup-shaped vessel of electrically insulating material partly submerged in the conducting liquid and adapted to receive a portion of the conducting liquid, said switching member having a plurality of separate liquid cells arranged substantially centrally about the'swinging axis of the switching member. spouts extending in diflerent angular directions from said liquid cells, and overflow edges arranged in said spouts so as to cause the liquid cells on the shifting of the switching member to be brought into communication with each other over said overflow edges.

6. In a switch as claimed in claim 5, wherein the spouts are so arranged as to substantially game each other with respect to the swinging "1.115 a switch as claimed in claim 5 includin the provision of flow resistances in the form of projections in the cells.

8. In a switch as claimed in claim 5, including the provision of a raised portion in the bottom of a liquid cell. V

9. In an electric switch, a closed vessel containing a conducting liquid connected to an outer electrode, a switching member pivotally mounted in the vessel and consisting of a cupshaped vessel of electrically insulating material partly submerged in the conducting liquid and adapted to receive a portion of the conducting" liquid, two separate liquid cells in said switching member provided with separate outer electrodes and positioned substantially at opposite sides of the swinging axis of the switching member, spouts extending in different angular directions from said liquid cells, and overflow edges arranged in said spouts so as to cause the liquid cells on the shifting of the switching member to be brought into communication with the liquid space of the outer vessel over said overflow edges.

10. Ina switch as claimed in claim 9 wherein the two spouts are arranged opposite each other at opposite sides of the swinging axis.

11. In an electric switch, a closed vessel containing a conducting liquid connected to an outer electrode, a switching member pivotally mounted in the vessel and consisting of a cupshaped vessel of electrically insulating material partly submerged in the-conducting liquid and adapted to receive a portion of the conducting liquid, said switch member having a plurality of separate liquid cells arranged side by side longitudinally of the swinging axis of the switching .member, spouts extending in different angular directions from said liquid cells, and overflow edges arranged in said spouts so as to cause the liquid cells on the shifting of the switching memher to be brought into communication with each other over said overflow edges.

12. In a switch as claimed in claim 11, having three liquid cells wherein the intermediate'cell g is provided with an aperture in open connection with the liquid space of the vessel, and said overflow edges being arranged in intermediate walls between the liquid cells so as to allow the liquid of the intermediate cell to be brought alternately 1 into contact with the liquid of the two other cells.

13. In an electric switch, a closed vessel contaming a conducting liquid connected to an outer electrode, a switching member pivotally mounted 33 in the vessel and consisting of a cup-shaped fl arranged substantially centrally about the swinging axis of the switching member, an overflow edge over which the liquid of the two cells may be brought into contact with each other in one angular position of the switching member, and another overflow edge over which the liquid contents of one of said cells may be brought into contact with the liquid of the vessel in another angular position of the switching member.

14. A switch as claimed in claim 13 in which the switching member is unsymmetrically shaped in such a manner as to be biased to a circuit closing position under the action of the upward pressure from the liquid in the vessel.

15. A switch as claimed in claim 5, in which the cup-shaped body is symmetrically formed so as to be biased to an intermediate position under the action of the upwardspressure from the liquid in the vessel.

16. In a switch as claimed in claim 1 in which the overflow edges are provided with means to cause the liquid flowing thereover to be divided into several streams.

KLAS WEMAN. 

